1. Field of the Invention:
This invention relates to brakes on locomotives and especially to means for improving the life of brake systems.
2. Description of the Prior Art:
Locomotives are supported from parallel rails by steel wheels. There are a plurality of axes which are perpendicular to the rails and support a wheel on either end, that is a left wheel on one rail and a right wheel on the other rail. In prior years, the diesel locomotives have used metallic brake shoes which are made from cast iron having certain other ingredients. Force is applied to the brake shoes to force them against the locomotive wheel. More recently, nonmetallic material has been developed and is used widely for use with brake shoes in lieu of the former cast iron material since the new material normally includes a composition of rubber and other components and has a higher coefficient of friction when in engagement with the steel wheels than the cast iron shoes.
One problem inherent in single brake shoes, which are widely used, remains. For example, the brake shoe wears out relatively rapidly and it becomes necessary to adjust the slack due to the wear thereon in order to maintain an efficient braking operation. U.S. Pat. No. 4,081,060 issued Mar. 28, 1978 to Roy H. Touchstone and entitled "Brake Adjustment Device for Converting Double Shoe Clasp-Type Brake Assembly to Single Shoe Brake Assembly" describes a widely used brake system. The brake adjuster described in that patent includes bracket means adapted to be secured to an end of the usual safety strap provided on the locomotive truck. Such system includes an independent slide bar attached to the bracket means and extending backwardly therefrom toward the wheels to be braked. A housing member is slidably disposed over the slide bar. The housing member terminates at its free end and the other end is secured to the brake levers. Complementary bores are provided in the slide bar and housing member in order to receive locking or keeper pins therethrough for securely retaining the housing member and slide bar in a preselected longitudinal relationship. The spacing between the bores is such as to provide substantially any desired longitudinal relationship between the slide bar and housing.
In the system just described, the slide bars are secured to the safety straps which is secured to the locomotive truck between the adjacent in-line wheels or adjacent one wheel and the relative position of the slide bar with respect to the wheels remain stationary. However, the housing members are in a longitudinal, reciprocal or floating relationship with respect to the respective slide bars and are in engagement with the brake levers. Thus, when the braking engagement between the brake shoe and the wheels must be adjusted for any reason, it is merely necessary to adjust the relative longitudinal position between the slide bar and the respective housing member and lock the two elements in the selected position by a keeper pin.
3. Problems with the Prior Art Braking Mechanism:
We have noticed that when brake assemblies using the slide bar and housing member just described that after awhile there develops "play" in the various pins and pivot points of the system. The locomotive wheels normally tend to slope slightly to the outside. Then, when the pivot points of the linkage system wear the brakes shoes will overhang, i.e., extend outwardly beyond the locomotive wheel so that the brake shoes are not in full contact as they should be. This can cause heat buildup to the point where it becomes a major problem and the locomotive car may be required to be removed from operations until corrections are made.
4. Object:
It is therefore an object of this invention to provide means whereby the brake shoes will not ride to the outside and have the overhanging problem.